1. The Field of the Invention
The present invention relates to exercise equipment and, more specifically, convertible exercise apparatus that produce elliptical foot displacement.
2. The Relevant Technology
A variety of indoor exercising equipment has been develop to exercise leg muscles commonly used in running, skiing, and other outdoor activities. Such machines include treadmills, stepping machines, and various types of sliding machines. Although effective to some extent, each of these machines has select disadvantages. For example, most treadmills wear quickly under the jarring of heavy jogging or running. Furthermore, treadmills have the drawback of producing high impact on the user's legs and knees. One approach that minimizes jarring is to use a stair stepper. Stair steppers, however, do not develop all of the muscles commonly used in running. Furthermore, such machines are difficult to use in sprint type exercises. Finally, sliding machines require the user to slide their feet back and forth along a horizontal plane. Such movement does not mimic running and thus exercises only a limited range of muscles.
Recent designs in exercise equipment have attempted to resolve some of the above problems by having a pair of spaced apart foot rails wherein each front end rotates in an elliptical path while each rear end moves along a horizontal plane. The center of each foot rail, on which the user's feet are positioned, also rotates in an elliptical path. This elliptical path is substantially similar to that commonly encountered during running. Likewise, since the user's feet never leave the foot rails, minimal impact is produced.
Several problems, however, have been encountered with such designs. For example, such apparatus commonly include a complexity of interrelated moving parts. This complexity increases the cost and time of manufacturing. An additional problem with such machines is that it is often difficult or impossible to adjust the path or movement of the foot pad to correspond with the stride of the user.
An additional problem with conventional elliptical displacement apparatus is that they are designed only for operation in one set standing position. As a result, the apparatus is limited to exercising one set group of muscles. If other muscles are to be exercised, a different apparats must be purchased.